Biomaterial Database

Threonine production by regulatory mutants of Serratia marcescens. 1978

S Komatsubara, and M Kisumi, and K Murata, and I Chibata

beta-Hydroxynorvaline (alpha-amino-beta-hydroxyvaleric acid)-resistant mutants of Serratia marcescens deficient in both threonine dehydrogenase and threonine deaminase were isolated and characterized. One of the mutants, strain HNr21, lacked feedback inhibition of threonine-sensitive aspartokinase and homoserine dehydrogenase, was repressed for the two enzymes, and produced 11 mg of threonine per ml of medium containing a limiting amount of isoleucine. The other mutant, strain HNr59, was constitutively derepressed for aspartokinase and homoserine dehydrogenase. Its kinase was sensitive to feedback inhibition, but its dehydrogenase was insensitive to feedback inhibition. This strain produced 5 mg of threonine per ml of medium containing either a limiting or an excess amount of isoleucine. Diaminopimelate auxotrophs derived from strain HNr59 produced more threonine (13 mg/ml) than the parent strain. However, similar auxotrophs derived from strain HNr21 produced the same amount of threonine as that produced by the parent strain.

UI	MeSH Term	Description	Entries
D007532	Isoleucine	An essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of LEUCINE. It is important in hemoglobin synthesis and regulation of blood sugar and energy levels.	Alloisoleucine,Isoleucine, L-Isomer,L-Isoleucine,Isoleucine, L Isomer,L-Isomer Isoleucine
D008239	Lysine	An essential amino acid. It is often added to animal feed.	Enisyl,L-Lysine,Lysine Acetate,Lysine Hydrochloride,Acetate, Lysine,L Lysine
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D003960	Diaminopimelic Acid	A diamino derivative of heptanedioic acid with amino groups at C-2 and C-6 and the general formula (COOH)CH(NH2)CH2CH2CH2CH(NH2)(COOH).	2,6-Diaminopimelic Acid,2,6 Diaminopimelic Acid,Acid, 2,6-Diaminopimelic,Acid, Diaminopimelic
D004352	Drug Resistance, Microbial	The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).	Antibiotic Resistance,Antibiotic Resistance, Microbial,Antimicrobial Resistance, Drug,Antimicrobial Drug Resistance,Antimicrobial Drug Resistances,Antimicrobial Resistances, Drug,Drug Antimicrobial Resistance,Drug Antimicrobial Resistances,Drug Resistances, Microbial,Resistance, Antibiotic,Resistance, Drug Antimicrobial,Resistances, Drug Antimicrobial
D006715	Homoserine Dehydrogenase	An enzyme that catalyzes the reduction of aspartic beta-semialdehyde to homoserine, which is the branch point in biosynthesis of methionine, lysine, threonine and leucine from aspartic acid. EC 1.1.1.3.	Dehydrogenase, Homoserine
D001222	Aspartate Kinase	An enzyme that catalyzes the formation of beta-aspartyl phosphate from aspartic acid and ATP. Threonine serves as an allosteric regulator of this enzyme to control the biosynthetic pathway from aspartic acid to threonine. EC 2.7.2.4.	Aspartokinase,Aspartate Kinase I,Aspartate Kinase II,Aspartate Kinase III,Aspartyl Kinase,Kinase I, Aspartate,Kinase II, Aspartate,Kinase III, Aspartate,Kinase, Aspartate,Kinase, Aspartyl
D012706	Serratia marcescens	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria found in soil, water, food, and clinical specimens. It is a prominent opportunistic pathogen for hospitalized patients.
D013912	Threonine	An essential amino acid occurring naturally in the L-form, which is the active form. It is found in eggs, milk, gelatin, and other proteins.	L-Threonine,L Threonine